/Engine/Source/Editor/UnrealEd/Public/EditorViewportLayoutThreePanes.h
Creates the viewports and splitter for the two panes vertical layout
virtual [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [SWidget](API\Runtime\SlateCore\Widgets\SWidget) > MakeViewportLayout ( [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [FAssetEditorViewportLayout](API\Editor\UnrealEd\FAssetEditorViewportLayout) > InParentLayout, const [FString](API\Runtime\Core\Containers\FString) & LayoutString )